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                    <span class="text-sm font-medium">数据结构探索</span>
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                <h1 class="hero-title text-4xl md:text-5xl lg:text-6xl mb-6">深入理解<span class="text-yellow-300">HashMap</span></h1>
                <p class="text-xl md:text-2xl opacity-90 mb-10 max-w-3xl mx-auto">
                    高效键值存储的奥秘与实现原理
                </p>
                <div class="flex flex-wrap justify-center gap-4">
                    <a href="#features" class="px-8 py-3 bg-white text-indigo-700 font-semibold rounded-full hover:bg-gray-100 transition duration-300 transform hover:-translate-y-1">
                        <i class="fas fa-feather-alt mr-2"></i>核心特性
                    </a>
                    <a href="#visualization" class="px-8 py-3 bg-indigo-700 bg-opacity-30 text-white font-semibold rounded-full hover:bg-opacity-40 transition duration-300 transform hover:-translate-y-1">
                        <i class="fas fa-project-diagram mr-2"></i>可视化解析
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    </section>

    <!-- Introduction -->
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                <div class="highlight">
                    <p class="text-lg font-medium">
                        <i class="fas fa-lightbulb text-yellow-500 mr-2"></i> 
                        <span class="font-bold">HashMap</span> 是一种高效的、基于哈希表的数据结构，广泛用于需要快速查找、插入和删除操作的场景。它具有键值对存储、哈希冲突处理、动态扩容、允许 <code>null</code> 键值等特性，但同时也是非线程安全的，需要在多线程环境中慎重使用。
                    </p>
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                <h2 class="text-3xl md:text-4xl font-bold font-serif mb-4 text-gray-800">
                    <i class="fas fa-star feature-icon mr-3"></i>HashMap核心特性
                </h2>
                <p class="text-gray-600 max-w-2xl mx-auto">
                    探索HashMap的11个关键特性，理解其高效实现背后的原理
                </p>
            </div>

            <div class="grid grid-cols-1 md:grid-cols-2 gap-8 max-w-6xl mx-auto">
                <!-- Feature 1 -->
                <div class="card feature-card bg-white p-8 rounded-lg">
                    <div class="flex items-start mb-4">
                        <div class="bg-indigo-100 text-indigo-600 rounded-full w-12 h-12 flex items-center justify-center mr-4">
                            <i class="fas fa-key text-xl"></i>
                        </div>
                        <div>
                            <h3 class="text-xl font-bold font-serif mb-2 text-gray-800">键值对存储</h3>
                            <p class="text-gray-600">
                                <code>HashMap</code> 是一个用于存储键值对的集合类，它允许通过键快速地查找、插入和删除对应的值。键和值都可以是任何类型的对象。
                            </p>
                        </div>
                    </div>
                </div>

                <!-- Feature 2 -->
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                            <i class="fas fa-fingerprint text-xl"></i>
                        </div>
                        <div>
                            <h3 class="text-xl font-bold font-serif mb-2 text-gray-800">键的唯一性</h3>
                            <p class="text-gray-600">
                                在 <code>HashMap</code> 中，每个键都是唯一的。如果试图插入一个已经存在的键，<code>HashMap</code> 不会添加新的键值对，而是会替换掉这个键原有的值。
                            </p>
                        </div>
                    </div>
                </div>

                <!-- Feature 3 -->
                <div class="card feature-card bg-white p-8 rounded-lg">
                    <div class="flex items-start mb-4">
                        <div class="bg-blue-100 text-blue-600 rounded-full w-12 h-12 flex items-center justify-center mr-4">
                            <i class="fas fa-question-circle text-xl"></i>
                        </div>
                        <div>
                            <h3 class="text-xl font-bold font-serif mb-2 text-gray-800">允许 null 键和值</h3>
                            <p class="text-gray-600">
                                <code>HashMap</code> 允许一个键为 <code>null</code>，并且可以有多个 <code>null</code> 值。在 <code>HashMap</code> 中，<code>null</code> 键通常会被存储在第一个桶中（即索引为 0 的位置）。
                            </p>
                        </div>
                    </div>
                </div>

                <!-- Feature 4 -->
                <div class="card feature-card bg-white p-8 rounded-lg">
                    <div class="flex items-start mb-4">
                        <div class="bg-green-100 text-green-600 rounded-full w-12 h-12 flex items-center justify-center mr-4">
                            <i class="fas fa-random text-xl"></i>
                        </div>
                        <div>
                            <h3 class="text-xl font-bold font-serif mb-2 text-gray-800">无序存储</h3>
                            <p class="text-gray-600">
                                <code>HashMap</code> 中的键值对是无序存储的，也就是说，插入的顺序并不会影响键值对在 <code>HashMap</code> 中的排列顺序。在遍历 <code>HashMap</code> 时，键值对的顺序可能与插入时的顺序不同。
                            </p>
                        </div>
                    </div>
                </div>

                <!-- Feature 5 -->
                <div class="card feature-card bg-white p-8 rounded-lg">
                    <div class="flex items-start mb-4">
                        <div class="bg-red-100 text-red-600 rounded-full w-12 h-12 flex items-center justify-center mr-4">
                            <i class="fas fa-table text-xl"></i>
                        </div>
                        <div>
                            <h3 class="text-xl font-bold font-serif mb-2 text-gray-800">哈希表实现</h3>
                            <p class="text-gray-600">
                                <code>HashMap</code> 基于哈希表实现，通过计算键的哈希值将其映射到内部数组的某个位置（桶），然后在该位置存储键值对。哈希表的实现使得 <code>HashMap</code> 能够提供快速的插入、删除和查找操作，时间复杂度平均为 O(1)。
                            </p>
                        </div>
                    </div>
                </div>

                <!-- Feature 6 -->
                <div class="card feature-card bg-white p-8 rounded-lg">
                    <div class="flex items-start mb-4">
                        <div class="bg-yellow-100 text-yellow-600 rounded-full w-12 h-12 flex items-center justify-center mr-4">
                            <i class="fas fa-code-branch text-xl"></i>
                        </div>
                        <div>
                            <h3 class="text-xl font-bold font-serif mb-2 text-gray-800">哈希冲突</h3>
                            <p class="text-gray-600">
                                由于哈希函数的限制，不同的键可能会映射到同一个桶中，这种情况称为哈希冲突。<code>HashMap</code> 采用链表或红黑树来处理哈希冲突：
                                <br><br>
                                + <strong>链表</strong>：在 JDK 8 之前，所有的冲突都是通过链表处理的，即将多个键值对存储在同一个桶的链表中。
                                <br>
                                + <strong>红黑树</strong>：从 JDK 8 开始，当链表长度超过一定阈值（默认为 8）时，链表会转换为红黑树，以提高性能。
                            </p>
                        </div>
                    </div>
                </div>

                <!-- Feature 7 -->
                <div class="card feature-card bg-white p-8 rounded-lg">
                    <div class="flex items-start mb-4">
                        <div class="bg-pink-100 text-pink-600 rounded-full w-12 h-12 flex items-center justify-center mr-4">
                            <i class="fas fa-expand text-xl"></i>
                        </div>
                        <div>
                            <h3 class="text-xl font-bold font-serif mb-2 text-gray-800">动态扩容</h3>
                            <p class="text-gray-600">
                                <code>HashMap</code> 会随着键值对数量的增加而自动扩容。当 <code>HashMap</code> 中的键值对数量超过了负载因子（默认 0.75）与当前容量的乘积时，它会将容量扩大一倍，并将所有键值对重新哈希到新的桶中。扩容操作会影响性能，因此在设计时应尽量减少扩容的频率。
                            </p>
                        </div>
                    </div>
                </div>

                <!-- Feature 8 -->
                <div class="card feature-card bg-white p-8 rounded-lg">
                    <div class="flex items-start mb-4">
                        <div class="bg-indigo-100 text-indigo-600 rounded-full w-12 h-12 flex items-center justify-center mr-4">
                            <i class="fas fa-lock-open text-xl"></i>
                        </div>
                        <div>
                            <h3 class="text-xl font-bold font-serif mb-2 text-gray-800">线程不安全</h3>
                            <p class="text-gray-600">
                                <code>HashMap</code> 是非线程安全的，这意味着如果在多线程环境中不加同步地对同一个 <code>HashMap</code> 实例进行操作，可能会导致数据不一致或其他意外情况。如果需要在多线程环境中使用，建议使用 <code>Collections.synchronizedMap</code> 方法来获得线程安全的 <code>HashMap</code>，或使用 <code>ConcurrentHashMap</code> 替代。
                            </p>
                        </div>
                    </div>
                </div>

                <!-- Feature 9 -->
                <div class="card feature-card bg-white p-8 rounded-lg">
                    <div class="flex items-start mb-4">
                        <div class="bg-purple-100 text-purple-600 rounded-full w-12 h-12 flex items-center justify-center mr-4">
                            <i class="fas fa-sync text-xl"></i>
                        </div>
                        <div>
                            <h3 class="text-xl font-bold font-serif mb-2 text-gray-800">迭代顺序不稳定</h3>
                            <p class="text-gray-600">
                                由于 <code>HashMap</code> 是无序的，因此在进行遍历时，键值对的顺序是不稳定的，可能会随着扩容或其他操作的发生而改变。
                            </p>
                        </div>
                    </div>
                </div>

                <!-- Feature 10 -->
                <div class="card feature-card bg-white p-8 rounded-lg">
                    <div class="flex items-start mb-4">
                        <div class="bg-blue-100 text-blue-600 rounded-full w-12 h-12 flex items-center justify-center mr-4">
                            <i class="fas fa-bolt text-xl"></i>
                        </div>
                        <div>
                            <h3 class="text-xl font-bold font-serif mb-2 text-gray-800">高效的查找和更新</h3>
                            <p class="text-gray-600">
                                由于其哈希表的结构，<code>HashMap</code> 提供了非常高效的查找和更新性能。一般情况下，<code>HashMap</code> 的查找、插入和删除操作的时间复杂度都是 O(1)。不过，最坏情况下，如果所有键都映射到了同一个桶中，性能会退化到 O(n)。
                            </p>
                        </div>
                    </div>
                </div>

                <!-- Feature 11 -->
                <div class="card feature-card bg-white p-8 rounded-lg">
                    <div class="flex items-start mb-4">
                        <div class="bg-green-100 text-green-600 rounded-full w-12 h-12 flex items-center justify-center mr-4">
                            <i class="fas fa-exclamation-triangle text-xl"></i>
                        </div>
                        <div>
                            <h3 class="text-xl font-bold font-serif mb-2 text-gray-800">迭代器的快速失败机制</h3>
                            <p class="text-gray-600">
                                <code>HashMap</code> 的迭代器是快速失败的（fail-fast），这意味着如果在迭代过程中，<code>HashMap</code> 的结构被修改（除了通过迭代器自身的 <code>remove</code> 方法），迭代器会抛出 <code>ConcurrentModificationException</code>。这是为了防止在多线程环境中并发修改时出现不一致的结果。
                            </p>
                        </div>
                    </div>
                </div>
            </div>
        </div>
    </section>

    <!-- Visualization Section -->
    <section id="visualization" class="py-20 bg-white">
        <div class="container mx-auto px-6">
            <div class="max-w-5xl mx-auto text-center mb-16">
                <h2 class="text-3xl md:text-4xl font-bold font-serif mb-4 text-gray-800">
                    <i class="fas fa-project-diagram feature-icon mr-3"></i>HashMap工作原理可视化
                </h2>
                <p class="text-gray-600 max-w-2xl mx-auto">
                    通过交互式图表直观展示HashMap的内部结构和关键概念
                </p>
            </div>

            <div class="hashmap-visual p-8 mb-12">
                <div class="mermaid">
                    graph TD
                        A[HashMap] --> B[键Key]
                        A --> C[值Value]
                        A --> D[哈希函数]
                        D --> E[计算哈希值]
                        E --> F[确定桶位置]
                        F --> G[处理哈希冲突]
                        G --> H[链表结构]
                        G --> I[红黑树结构]
                        A --> J[负载因子]
                        J --> K[扩容机制]
                        A --> L[线程不安全]
                        A --> M[迭代器快速失败]
                        style A fill:#667eea,stroke:#333,color:#fff
                        style B fill:#9f7aea,stroke:#333,color:#fff
                        style C fill:#667eea,stroke:#333,color:#fff
                        style D fill:#4c51bf,stroke:#333,color:#fff
                        style E fill:#6b46c1,stroke:#333,color:#fff
                        style F fill:#553c9a,stroke:#333,color:#fff
                        style G fill:#7f9cf5,stroke:#333,color:#333
                        style H fill:#a3bffa,stroke:#333,color:#333
                        style I fill:#7f9cf5,stroke:#333,color:#333
                        style J fill:#4c51bf,stroke:#333,color:#fff
                        style K fill:#6b46c1,stroke:#333,color:#fff
                        style L fill:#e53e3e,stroke:#333,color:#fff
                        style M fill:#f56565,stroke:#333,color:#fff
                </div>
            </div>

            <div class="grid grid-cols-1 md:grid-cols-2 gap-8 max-w-5xl mx-auto">
                <div class="bg-indigo-50 p-6 rounded-lg">
                    <h3 class="text-xl font-bold font-serif mb-4 text-indigo-800">
                        <i class="fas fa-lightbulb mr-2"></i>最佳实践
                    </h3>
                    <ul class="space-y-3">
                        <li class="flex items-start">
                            <i class="fas fa-check-circle text-green-500 mt-1 mr-2"></i>
                            <span>合理设置初始容量和负载因子以减少扩容次数</span>
                        </li>
                        <li class="flex items-start">
                            <i class="fas fa-check-circle text-green-500 mt-1 mr-2"></i>
                            <span>为键对象实现良好的hashCode()和equals()方法</span>
                        </li>
                        <li class="flex items-start">
                            <i class="fas fa-check-circle text-green-500 mt-1 mr-2"></i>
                            <span>多线程环境使用ConcurrentHashMap替代</span>
                        </li>
                        <li class="flex items-start">
                            <i class="fas fa-check-circle text-green-500 mt-1 mr-2"></i>
                            <span>避免使用可变对象作为键</span>
                        </li>
                    </ul>
                </div>

                <div class="bg-purple-50 p-6 rounded-lg">
                    <h3 class="text-xl font-bold font-serif mb-4 text-purple-800">
                        <i class="fas fa-exclamation-triangle mr-2"></i>注意事项
                    </h3>
                    <ul class="space-y-3">
                        <li class="flex items-start">
                            <i class="fas fa-times-circle text-red-500 mt-1 mr-2"></i>
                            <span>多线程环境下会导致数据不一致</span>
                        </li>
                        <li class="flex items-start">
                            <i class="fas fa-times-circle text-red-500 mt-1 mr-2"></i>
                            <span>性能对哈希函数质量高度敏感</span>
                        </li>
                        <li class="flex items-start">
                            <i class="fas fa-times-circle text-red-500 mt-1 mr-2"></i>
                            <span>迭代顺序不可预测</span>
                        </li>
                        <li class="flex items-start">
                            <i class="fas fa-times-circle text-red-500 mt-1 mr-2"></i>
                            <span>扩容操作开销较大</span>
                        </li>
                    </ul>
                </div>
            </div>
        </div>
    </section>

    <!-- Performance Comparison -->
    <section class="py-16 bg-gray-50">
        <div class="container mx-auto px-6">
            <div class="max-w-4xl mx-auto">
                <h2 class="text-3xl font-bold font-serif mb-8 text-center text-gray-800">
                    <i class="fas fa-tachometer-alt feature-icon mr-3"></i>时间复杂度比较
                </h2>
                
                <div class="overflow-x-auto">
                    <table class="min-w-full bg-white rounded-lg overflow-hidden">
                        <thead class="bg-indigo-600 text-white">
                            <tr>
                                <th class="py-3 px-4 text-left font-semibold">操作</th>
                                <th class="py-3 px-4 text-left font-semibold">平均情况</th>
                                <th class="py-3 px-4 text-left font-semibold">最坏情况</th>
                            </tr>
                        </thead>
                        <tbody class="divide-y divide-gray-200">
                            <tr>
                                <td class="py-3 px-4 font-medium">查找(get)</td>
                                <td class="py-3 px-4">O(1)</td>
                                <td class="py-3 px-4">O(n)</td>
                            </tr>
                            <tr class="bg-gray-50">
                                <td class="py-3 px-4 font-medium">插入(put)</td>
                                <td class="py-3 px-4">O(1)</td>
                                <td class="py-3 px-4">O(n)</td>
                            </tr>
                            <tr>
                                <td class="py-3 px-4 font-medium">删除(remove)</td>
                                <td class="py-3 px-4">O(1)</td>
                                <td class="py-3 px-4">O(n)</td>
                            </tr>
                            <tr class="bg-gray-50">
                                <td class="py-3 px-4 font-medium">遍历</td>
                                <td class="py-3 px-4">O(n)</td>
                                <td class="py-3 px-4">O(n)</td>
                            </tr>
                        </tbody>
                    </table>
                </div>

                <div class="mt-8 p-6 bg-yellow-50 border-l-4 border-yellow-400 rounded">
                    <div class="flex">
                        <div class="flex-shrink-0">
                            <i class="fas fa-info-circle text-yellow-500 text-xl"></i>
                        </div>
                        <div class="ml-3">
                            <h3 class="text-lg font-medium text-yellow-800">性能分析</h3>
                            <p class="mt-2 text-yellow-700">
                                尽管HashMap在最坏情况下性能会退化，但在实际应用中，通过良好的哈希函数设计和合理的容量规划，可以确保绝大多数操作都在O(1)时间内完成。JDK 8引入的红黑树优化进一步降低了最坏情况下的性能损失。
                            </p>
                        </div>
                    </div>
                </div>
            </div>
        </div>
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    <script>
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```